change function to take reference rather than shared_ptr (#1238)

src/ngraph/op/batch_norm.cpp

@@ -267,7 +267,7 @@ void ngraph::op::BatchNorm::generate_adjoints(autodiff::Adjoints& adjoints,
     //Please see `add_output` in `BatchNorm::BatchNorm` for more details
     if (this->get_training_flag() && get_input_size() == 3)
     {
-        auto goes = op::get_output_elements(this->shared_from_this());
+        auto goes = op::get_output_elements(*this);
         mean = goes.at(1);
         var = goes.at(2);
     }

src/ngraph/op/get_output_element.cpp

@@ -54,11 +54,11 @@ void op::GetOutputElement::generate_adjoints(autodiff::Adjoints& adjoints, const
     adjoints.add_delta(get_inputs().at(0).get_output().get_node(), delta, get_n());
 }
 
-NodeVector op::get_output_elements(const std::shared_ptr<Node>& mon)
+NodeVector op::get_output_elements(const Node& mon)
 {
-    NodeVector goes(mon->get_outputs().size());
+    NodeVector goes(mon.get_outputs().size());
 
-    for (auto goe_input : mon->get_output_inputs(0))
+    for (auto goe_input : mon.get_output_inputs(0))
     {
         auto goe = std::dynamic_pointer_cast<op::GetOutputElement>(goe_input->get_node());
         goes.at(goe->get_n()) = goe_input->get_node();

src/ngraph/op/get_output_element.hpp

@@ -22,7 +22,7 @@ namespace ngraph
 {
     namespace op
     {
-        NodeVector get_output_elements(const std::shared_ptr<Node>& mon);
+        NodeVector get_output_elements(const Node& mon);
 
         /// \brief Operation to get an output from a node.
         class GetOutputElement : public Node